Brake and sanding control means



May 27, 1941. B. s. AIKMAN 2,243,450

K BRAKE AND SANDING CONTROL MEANS Original Filed Jan. 12, 19.40 2 Sheets-Sheet l l ATTORNEY Original Filed Jan. l2, 1940 2 Sheets-Sheet 2- BURTO NSAIKMAN MyW-4 ATTORNEY Patented May 27, i941 BRAKE AND SANDING CONTROL IWEAN S Burton S. Aikman, Wilkinsburg, Pa., assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania @riginal application January 12, 1940', Serial No. 313,513. Divided and this application March 30, 1940, Serial No. 326,927

s claims. (c1. 291-42) This invention relates to fluid pressure brake and sander controlling means, and more particularly to means for controlling the application of the brakes and sanding of the rails in a manner to inhibit or wholly prevent sliding -of vehicle wheels during application of the brakes. The present application is a division of my copending application, Serial No. 313,513, which was filed in the United States Patent Oice January 12, 1940.

It is well known that sliding of vehicle wheels due to application of the brakes thereon is objectionable, both because of damage done to the wheels and because of the reduced retarding effect which is produced by a sliding wheel. As a consequence, it is desirable that means be provided which will detect an incipient stage of wheel sliding and then operate immediately to correct the condition and permit the wheel to assume normal rotation. The incipient stage of wheel sliding is generally referred to as a slipping condition of the wheel, that is to say, a wheel is said to slip when it rotates at a speed below that of non-slipping wheels, and is said to slide when not rotating at all and held in a locked state.

An object of the invention is to provide fluid pressure controlled means having a mechanism operatively responsive to an abnormal or sudden reduction in the rotative speed of a vehicle wheel, resulting in initial slipping thereof during application of the brakes, to effect automatic sanding of the rails, followed by quick release of the braking force when necessary, thereby preventing sliding of the wheels.

It is a further object of the invention to provide a brake and sanding control apparatus including means responsive to abnormal change in the rotative speed of the wheel of the vehicle to effect supply of sand to the rail in advance of the wheel regardless of the direction in which the vehicle is moved.

Other objects and advantage-s of the invention will appear in the following more detailed description thereof, taken in conjunction with the accompanying drawings, in which Fig. 1 is a diagrammatic elevational View, mainly in section, of a fluid pressure brake and sanding control equipment embodying features of the invention; and

Fig. 2 is an enlarged detail sectional View of a portion of the control mechanism shown in Fig. 1.

Description According to the invention as embodied in the equipment shown in Fig. 1 of the drawings, there is provided a brake cylinder device It which is suitably connected through the medium of rigging means, not shown, to the usual brake mechanism associated with a wheel and axle assembly I I of a railway truck. The truck is illustrated in fragmentary form and includes a truck frame I2 adapted to be supported on a journal box I3. The braking equipment further comprises a self-lapping brake valve device I4, a reservoir I5, a brake release valve device I6, a pair of sanding devices I1 and I8, and adeceleration control valve mechanism indicated generally by the character 23.

The brake cylinder device I0 comprises a casing 22 within which is slidably mounted a piston 2li dividing the casing into chambers 23 and 2l. The piston is operatively connected by means of a piston rod 25 to the usual brake rigging, not shown. The piston rod is contained within a sleeve element 25a, which isl slidably iitted in an aperture in the end 2| of the casing, and has formed therein a relief port 29. A release spring 26 is mounted within the chamber 2l for moving the piston 24 toward release position when fluid under pressure is released from the chamber 23, or when iiuid under pressure is supplied to the chamber 21, as hereinafter explained. The piston chamber 23 is adapted to be supplied with iiuid under pressure through the medium of a pipe 28, which is connected with the supply port of the self-lapping brake valve device it and may extend throughout the train.

The brake release valve device E3 is adapted to respond to operation of the deceleration control valve device 20, as hereinafter explained, to control the supply of fluid under pressure to the chamber 2l of the brake cylinder device l@ for the purpose of preventing sliding of the wheels. This valve device comprises a casing having a valve chamber 30 communicating with a fluid pressure supply pipe 3|, within which chamber is mounted a valve 32 that is carried by a piston 33 and is adapted to engage a valve seat rib 34 formed in the casing. The valve 32 controls'communication from the valve chamber 3Q to a bore 35, which communicates by way of a pipe 3E with the chamber 21 of the brake cylinder device I3. The piston 33 is subject to the opposing pressures of fluid in the valve chamber 30 and in a chamber 38, which communicates with a conduit 39 leading to a communication in the deceleration control valve device 20 hereinafter described. Y. A restricted passage 40 formed in the piston 33 provides communication between the chambers 38 and 30.

The valve S2 has a stem 4| which extends through the bore and into a spring chamber 42 communicating through a port 43 with the atmosphere, which stem is normally urged downwardly to hold the valve 32 in seated position under the pressure of a spring t4 that is interposed between a collar carried by the ste.. and a Valve element 46 slidably mounted thereon. The valve element 4S is in turn urged into seated engagement with a seat rib 41 formed on the casing, under the -force exerted by the spring 44, for closing communication between the bore 5 and the atmospheric chamber 42..-

The sanding devices |1 and i3 are similarly constructed, and are secured by bolts or other suitable means on downwardly extending strut members and 5|, which form portions of the vehicle frame l2 and are ydisposed on opposite sides of the usual journal box |3 associated with the wheel and axle assembly The sanding device |8 is illustrated partly in section, and com*- prises a sand hopper having formed on the lower side thereof a portion 5S, in which is formed a sand chamber 51 that communicates with a sand discharge pipe 58 adapted to direct flow of sand to the rail adjacent the wheel. Sand contained in the hopper 55 is adapted to ow under the force of gravity into the sand chamber 51, where it is normally retained by a bale Wall formed on the casing within the chamber. A nozzle 6| communicating with a conduit 62 and mounted in the casing portion 56 within the sand chamber 51 is adapted to direct flow of fluid under pressure through the chamber for driving sand over the baffle wall E5 and through the sand pipe 58. The conduit 62 is adapted to be supplied with fluid under pressure in response to operation of the deceleration control valve device 20 as hereinafter explained.

It will be understood that the sanding device |1 has the same construction as that of the sanding device I8. The sanding mechanism |1 is adapted to be supplied with uid under pressure by way of a conduit t4 tor depositing sand on the rail through the medium of a sanding pipe 65. Y

The acceleration control valve device 20 comprises a casing structure including a main section 10 secured by suitable means, such as bolts 1|, to the journal box i3, a reservoir portion 14, a pump portion 15, and a valve portion 1S. Formed within the reservoir portion 14 of the casing structure is a liquid supply chamber 18 which is adapted to be iilled with a suitable liquid, such as oil. The pump portion 15 or" the casing structure is disposed partly within the chamber 18 and has formed therein a pair of connected circular chambers 19 within which are rotatably mounted two intermeshed pumping gears 80 and 8|. The gear Si is mounted on a pin or shaft 83 which is suitably journaled in the casing structure, and the other gear 80 may be secured to an extension ||a of the vehicle axle by means of a key 8d. The pumping gears 00 and 8| are adapted to be operated to supply liquid from the supply chamber 18 to either of two oppositely disposed receiving passageways S5 and 81, depending upon the direction of rotation of the wheel and axle assembly as hereinafter explained.

The passageway 85 communicates with an inlet valve chamber 8S which contains an inlet valve 89 for controlling communication to the valve chamber from a vertically disposed intake conduit 00 that extends to the lowermost portion of the supply chamber 13. Similarly, the passageway 81 communicates with an inlet valve chamber 92 containing an inlet valve S3 which controls communication between the valve charnber and an intake pipe 94 opening into the supply reservoir 18. Both of the passageways S3 and 81 also communicate with discharge valve chambers 9S and 01, respectively, which are connected together by way of a passage 08. Discharge valves 99 and |00 are disposed in the valve chambers S5 and 01 for preventing baci: flow of liquid to the respective passageways and 81.

Formed in the valve section 16 of the casing structure and preferably extending longitudinally thereof is a bore |02, which communicates directly with the discharge valve chamber 91 and by way of passage 98 with the discharge valve chamber 96. Slidably mounted in the bore |02 isY a piston |03 having formed at one side thereof a chamber |04. The piston |03 is adapted to vary the flow area of a port |0$ connecting the bore |02 with a passageway |01, which communicates by way of a discharge chamber |08 and pipe |00 with the liquid supply reservoir 18. The port |05 has a restricted portion I06a through which liquid can flow at a restricted rate from the bore |02 to the passageway |01 when the piston |03 is disposed in the normal position thereof, as shown in Fig. 1 of the drawings. The passageway |61 also communicates with the chamber |94 through a restricted port ||0, and also by way of a valve chamber containing a release ball check valve H2. The ball check valve I|2 is urged toward seated position under the force of a spring H3, so that liquid can flow from the passageway |01 to the chamber |04 only by way of the restricted port H0, while flow of liquid in the opposite direction may be affected both by way of the port I0 and past the check valve.

n The piston |03 has a longitudinal bore ||5 in which is slidably mounted a smaller piston I5 having secured thereto a hollow stem |1 that is slidably mounted in a bore formed in an extension ||3 of the larger piston |03, which extension is in turn slidably mounted in a bore extending between the bore |02 and chamber |08. The hollow stem |1 is provided with openings |2| connecting the bore ||5 through the interior passage |22 of the stem with openings |23, which communicate with the chamber |68 at all times. At the side of the piston ||5 opposite the bore ||5 is formed a valve chamber |25, within which is mounted a release valve |26 that is adapted to control communication between the valve chamber |25 and the chamber |04. The release valve |25 is provided with a restricted port |28 for permitting restricted communication between the chambers |25 and |04 at all times, andvis normally urged into seated engagement with an annular seat member |29 which is interposed between the end of the piston |03 and a coil spring |30 mounted within the chamber |04. The release valve |25 is thus urged toward seated position under the force of a small coil spring |3| which is interposed between a collar on the end of a stem |32 of the valve, and an apertured seat member |33 engaging the scat member |29. e

To the end of the hollow stein ||1 within the chamber |08 is secured a valve stem |33, which is slidably mounted in a bore |31 formed in the casing and has a fluted portion |33 carrying a valve |39. 'Ihe valve |39 is disposed in a valve chamber |40 and is urged toward seated position under the force of a spring |42 for normally closing communication between the valve chamber and a passage |43 communicating with a valve chamber |44. The valve chamber |40 is connected by way of a passage |45 with the conduit 39 leading to the piston chamber 38 of the brake release valve device |8. The valve |39 is adapted to control the supply of fluid under pressure to either of the sanding devices and |8 in accordance with operation of a sanding selec-- tor mechanism, which includes a valve element |48 disposed Within the valve chamber |44 and connected by means of a stern |49 with a. valve |50 that is disposed within a valve chamber formed in the casing. The valve |48 is adapted to control communication from the chamber |44 by way of the bore containing the stem |49 to the sanding conduit 62, and carries a cage portion |53 having slidably mounted therein a plunger terminating ina valve |54, which is adapted to control communication from the chamber |44 through a passage |55 to the other sanding conduit 64. A coil spring |51 is interposed between the upper surface of the Valve |48 and the lower surface of the plunger ,carrying the valve |54 for urging said elements apart, the spring being of such length as to hold the valve |54 in seated position only when the valve |48 is lifted from its seat as hereinafter explained. The chamber I5| is open to the atmosphere by way of an opening |80 and has slidably mounted therein a piston ll, which is adapted to operate the valves |50 and |48 and has formed at the lower side thereof a chamber |62 communicating by way of a passage |83 with the chamber 92. A coil spring |84 is interposed between a Wall of the chamber |5| and the piston |52 for normally positioning the piston as shown in IBI, and for thereby maintaining the valve |48 in seated position.

Operation When the Vfluid. pressure brake equipment shown in Fig. 1 is in condition for operation, fluid under pressure supplied to the reservoir i5 in the usualmanner flows therefrom through the supply pipe 3| to the chamber 30 of the brake release Valve device I8, and thence iiows by way of the restricted port 40 in piston 33 to the piston chamber 38, and throughthe conduit 39 and passage |45 to the Valve chamber |40 in the deceleration control valve device 20. It will be understood that the coil spring |22 normally maintains the valve |39 in seated position as shown in the drawings. With the brake valve device |4 in release position, the piston chamber 23 in the brake cylinder device l0 is maintained in communication with the atmosphere by way of the pipe 28 and the usual communications in the brake Valve device.

Assuming that the vehicle is operated along the track in a direction to cause rotation of the wheel and axle assembly in a counterclockwise direction, it will be apparent that the pumping gears 80 and 8| are driven at a speed corresponding to the rotative speed of thc'wheel to draw liquid from the supply chamber 18 through the intake pipe 94, past the check valve 93, and thence through the chamber 92 and passage 81 to the gear chambers 19, from which liquid is forced through the passage 86, past the discharge check valve 99, and through the chamber 99, passage 98 and chamber 91 to the bore |02. The pressure of liquid thus supplied to the bore .l 02 acts against the piston |03 to move the piston against the opposing force of the spring and thus causes the piston to partially uncover the port |08, through which liquid under pressure then ows to the passageway |01. Liquid in the passageway |01 is free to flow therefrom to the chamber |08 and pipe |09 and thus to return to the supply chamber 18.

Liquid thus supplied to the passageway |01 also flows through the restricted passage ||0 to the chamber |04, and thence by way of the restricted port |28 in the valve |26 to the chamber |25. I have found that the liquid will displace any air initially filling these chambers after a short period of operation.V

It will be understood that the extent of movemzent of the piston |03 to uncover the port |08 is determined by the pressure of liquid supplied to the bore |02 by operation of the pumping gears 80 and 8|, which are in turn driven in accordance with the speed of rotation of the associated wheel of the vehicle. As the speed of the vehicles increases, the piston |03 will consequently be moved farthertoward the left-hand in order to permit increased flow through the port |08 of liquid under pressure supplied by the pumping gearsV 80 and 8|. As the piston |03 thus moves against the force of the spring |30, the spring seat member |29 and valve |28 are carried with the piston while liquid is at the sainte time forced from the chamber |04 through the restricted port |28 of the valve into the chamber |25. The smaller piston ||8 of course remains stationary at this time due to engagement of the valve |39, carried on the end of the piston stem, with its seat.

The pressure of liquid within the chambers |25 and |04 is substantially the same as the uid pressure within passage |01, chamber |08 and the supply chamber 1,8, which at this time may be approximately atmospheric pressure. The pressure of liquid Within the intake pipe 94 and valve chamber 02 through which liquid is drawn by operation of the pumping gear is somewhat less than the fluid pressure in the supply chamber 18, so that the piston ISI, which is'subject to the pressure of liquid supplied to chamber |62 from valve chamber 92, is held in the normal position as shown in Fig. 1, under the force of spring |04. The sanding valves |48 and |49 are thus maintained in their respective seated and unseated positions, while the valve |54 is held in unseated position.

When it is desired to eiect an application of the brakes, the self-lapping brake valve device I4 is operated to effect supply of iiuid under pressure from the reservoir l5 to the supply pipe 28 and thence to the piston chamber 23 of the brake cylinder device I0. The piston 24 is thereby moved against the force of the spring 26 and through the medium of the piston rod 25 and associated brake rigging members, not shown, effects application of the usual brake shoes or other braking means to the wheel and axle assembly The portion of the sleeve member 25a. having the port 29 is thus carried outwardly of the cylinder end 2|.

If the consequent deceleration of the vehicle is elected at a rate corresponding to the rate of deceleration of the wheel so that any tendency of the wheel to slip on the rail is avoided, the pressure of liquid supplied to the bore |02 by the pumping gears 80 and 8| is reduced gradually, so that the spring |30 is permitted to shift the spring seat member |29, valve |28, and piston |03 to the right slowly enough to force liquid from the chamber through the restricted port |28 to chamber |04 hout exerting suflicient pressure on the piston I3 to overcome the force of spring |42. The valve 39 is thus still maintained in seated position.

If, however, the application of the brakes causes retardation of the wheel il at an excessive rate, so that the wheel begins to slip with respect to the rail, the relatively rapid reduction in speedrof operation of the pumping gears 8i) and 8| effects a correspondingly quick reduction in the pressure of liquid in the bore |02 acting on the piston |03. The spring |33 is thereby enabled to shift the spring seat member 12S, valve |23 and piston 03 toward the normal position at a speed somewhat in excess of that which would permit complete displacement of liquid from the chamber |25 by way of the restricted port 23, so that liquid is momentarily entrapped within 'the chamber E25 and thus transmits sufficient pressure exerted by the spring IS through the medium of the stem andvalve |33 to overcome the force of spring |42.

The valve |39 is thereby moved slightly away from its seat for permitting relatively restricted iiow of fluid under pressure therepast, it being understood that the valve is not, under the operating condition now being described, moved to its fully unseated position. Fluid under pressure is supplied at a relatively slow rate of flow from the supply pipe 3| through the chamber in the brake release valve device i3, the restricted port in the piston 33, chamber 32,

conduit 3Q, 4passage |45 in the deceleration control valve device 2s, and then past the slightly unseated valve |39 and through passage |43, chamber 44, passage |55 and conduit 04 to the sanding device il, which is thereby operated to supply sand through the san-ding pipe to the rail in advance of the wheel The presence of sand on the rail will usually increase the coefcient of friction between the rail and wheel suiciently to cause the wheel to pick up or increase its rotative speed in time to avoid serious wheel slipping. Upon the resultant increase in the speed of operation of the pumping gears Se and 8|, further reduction in pressure of liquid in the bore |532 is prevented. Meanwhile, due to continued flow or liquid from the chamber |25 through the restricted port |28 of valve |23, the spring |42 becomes effective to permit the piston H0 to be returned to its normal position under the force of the spring |42, While the valve |39 is again moved to seated position. Further supply of sand to the rails is thus stopped.

Let it now be assumed that an application of the brakes is eiected with such force as to cause deceleration of the wheel and axle assembly i i at a rate in excess of the maximum ratey permissible without causing wheel sliding, with the result that the speed of operation of the pumping gears B0 and 8| is rapidly reduced, thus causing a relatively sudden decline in the pressure oi liquid supplied to the bore |02. Upon the quick reduction of liquid pressure within the bore 32 he piston S03 and spring seat member 229 are rapidly shifted under the force of the spring |39 toward normal position. As the spring seat member |23 and the valve 20 seated thereon are thus quickly moved toward the piston i5, liquid is entrapped therebetween due to the slo-w rate of ow permitted by the restricted port |28, and the piston vI i3, stem and` valve |33 are consequently forced to the right under the pressure of the spring |30 in opposition to the pressureof the spring |42. Because of the sudden movement of the piston |03, spring seat member |29 and valve |25 under the force of the spring |30 as just explained, only a relatively small amount of the liquid entrapped within the chamber |25 has time to flow therefrom to the chamber |04 by way of the restricted -port |28, so that substantially the full force of the spring |30 is transmitted to the piston Ht, which is thus operated to move the valve |33 to its fully unseated position.

With the valve |39 thus unseated, fluid under pressure is vented from the piston chamber 38 of brake release valve device |6 by way of the conduit 39, past the unseated Valves |39 and |54 and through conduit 64 to the sanding device I1 at a faster rate than that of ow of fluid from the chamber 30 through the restricted port 40 -in piston 33. Consequently, while the sanding device is thereby operated in the usual manner to eect supply of sand through the sanding pipe to the rail in advance of the wheel, the pressure of fluid in the chamber 30 moves the piston 33 upwardly and thereby lifts the valve 32 away from the seat rib 34, the valve 46 being meanwhile maintained in engagement with the seat rib 4l under the force of the spring 44, which force is now greater than is normally the case, due to compression of the spring. When the valve 32 is thus unseated, fluid under pressure is supplied from the supply pipe 3| by way of the chamber 30 and pipe 36 to the chamber 2l in the brake cylinder device I0, the piston 24 of which is then quickly moved toward release position by the force of the spring 26 upon substantial equali- Zation of the pressures in chambers 23 and 21.

In response to the release of the brakes initiated as just explained, the wheel and axle assembly I l, aided by the increased traction resulting from the depositing of sand on the rail, again picks up speed until the rotative speed thereof corresponds with that of the vehicle, while the pumping gears 60 and 8| are driven to increase the supply of i. liquid under pressure to the bore |02 for again shifting the piston |703 and associated elements to the left against the force of the spring |30. Upon the quick movement of the piston |03 as just explained, the liquid within the chamber 04 is for a time subjected to a slightly increased pressure, since flow of liquid from the chamber through the restricted passage IIO to thepassageway |01 is restricted while the spring ||3 resists opening of the check Valve ||2, and the valve |26 is consequently unseated against the biasing force of the spring |3| for admitting liquid under pressure from the chamber |04 to the chamber 25, where lthe pressure of the liquid is effective through the medium of the piston I6 and stem to maintain the valve |39 unseated.

It will thus be seen that, during such time as is required for the speed of rotation of the axle assembly to increase from the rate at which it began to slip to a rate corresponding to the vehicle speed, fluid under pressure is continuously supplied from the piston chamber 38 of brake release valve devicev l5 to the sanding device 1, while the valve 32 is maintained unseated for supplying huid under pressure to the chamber 21 of the brake cylinder device I0, as hereinbefo'r explained. In other Words, the rail is sanded and Ythe brakes held released to permit complete restoration of the rotative speed of the wheel and axle assembly to la rate corresponding with the speed of the vehicle.

The return of the rotative speed of the wheel to a value corresponding to the Speed of the vehicle, following the temporary release of the brakes as explained, is usually effected rapidly, and while the brakes associated with other wheels of a vehicle are still maintained applied. It is consequently desirable that a reapplication of the brakes for the wheel be effected automatically after the wheel slipping condition has been corrected.

After movement of the piston I G3 under the increased pressure of liquid in the bore |02 has been completed during restoration of the rotative speed of the wheel to the vehicle speed, the pressure of liquid in the connected chambers |94 and |25 again becomes equalized with that of the passageway |91. The valve |39, which had been maintained unseated by the pressure of liquid in the chamber |25 during the aforementioned operation of the acceleration control valve device 20, is then moved to the left to seated position under the force of the spring |42, the stem H1 and piston i6 being moved in the lsame direction to expel liquid from the chamber |25 through the restricted port |28 in valve |26, which is meanwhile returned to seated position by the spring I3 When the valve |39 is thus moved to seated position, further dow of fluid under pressure to the passage M3 and thence to the sanding device |1, is stopped, while the pressure of fluid in the chamber 38 of the brake release valve device IS is quickly increased toward equalization with the fluid pressure in chamber 39, by flow of uid through the restricted port 49. When the fluid pressures in chambers 30 and 38 become equalized, the piston 33 is operated to move valve 32 into engagement with the seat rib 34, under the force exerted bythe spring 44 on the stem 4|, so that Ythe supply of fluid under pressure to the chamber 21 of the brake cylinder device I0 is cut oir, while fluid under pressure beginsto flow, from the chamber 21 to atmosphere by way of pipe 35, bore 35, and past the valve member 46. The spring 44 at this time exerts only its normal force to oppose unseating of the valve, since the collar 45 has been returned to the lower position as shown in Fig. 1.

Assuming that the supply of fluid under pressure by way of the brake valve device I4 and the pipe 23 to the piston chamber 23 of the brake valve device is still continued, the piston 24 is again forced to the right against the pressure of the spring 26 for effecting reapplication of the brakes. The spring 44, however, is adapted to move the valve element 46 into engagement with the seat 41 for cutting off complete flow of uid under pressure from the spring chamber 21 when the fluid pressure therein has been reduced to a predetermined value, it being understood that the port 29 of the sleeve 25a is still held outwardly of the end 2| of the brake cylinder casing, so that the iiuid pressure acting in the chamber 23 on the brake cylinder piston 24 is not eiective to cause reapplication of the brakes to the same degree of force as existed priorv to the slipping of the wheel.

V'When it is desired to elect the release of all brakes on the vehicle, the valve device |4 is moved to release position for venting the pipe 28 and brake cylinder chamber 23 to the atmosphere, whereupon the spring 22 moves the piston 24 and rod 25 to release position. As the port 29 in the hollow brake cylinder rod 25 is thus brought into communication with the chamber 21, the fluid under pressure remaining therein is discharged to the atmosphere, so that the brake cylinderdevice is then in condition for subsequent operation to eiect application of the brakes in the usual manner.

If `the vehicle is driven along the rail in the opposite direction, so that the Wheel and axle assembly is rotated in a clockwise direction, the pumping gear 83 is likewise rotated in a clockwise direction for turning the pumping gear- 8| in a counterclockwise direction, thereby drawing liquid from the supply reservoir 18 through the intake pipe 9B, plast inlet valve 89, and through chamber 88 to the chamber 19, from which the liquid is forced under pressure through ythe passage 81 and past the discharge valve Hill to the bore |02 for operating the piston |93 in the manner hereinbefore explained. At the same time liquid under pressure is supplied from the passage 81 through chamber 92 and passage |93 to the piston chamber |62, and moves the piston |6| upwardly against the force of the spring |34, thereby seating the valve |50 and unseating the valve |48. As the valve |48 is moved upwardly and away from its seat the valve |54 is lifted into seated position under the pressure of thespring |51. The several valve elements are thus positioned to condition the sanding device i3 for operation, While the sanding mechanism |1 at the trailing side of the Wheel and axle assembly is rendered inoperative.

lf an application of the brakes is now effected with excessive force, causing the Wheel to slip with respect to the rails so as to elect operation of the deceleration control valve device 2E! in the manner hereinbefcre explained, the consequent unseating of the valveV |39 Will elfect supply of liuid under pressure in the usual Inanner from the valve chamber |40 and through the passage |453 and chamber |44, past the unseated valve |43, and through the conduit 62 and nozzle 5l to sand chamber 51 of sanding device i8. Sand is thereby driven from the sand chamber and through the sand pipe 58 to the rail in advance of the Wheel |I.

From the foregoingit will be apparent that a brake control equipment constructed in accordance with my invention comprises liquid vpumping means operative in accordance With the rotative speed of a vehicle wheel to vary the pressure of liquid acting on a movable abutment, which is responsive to a sudden reduction in said pressure to cause quick release of the brakes to prevent sliding of the Wheel, and is responsive to subsequent pick-up in rotative speed of the wheel to permit reapplication ofthe brakes. According to a further feature of the invention, sanding means `is provided for supplying sand to the rail in advance of the wheel upon operation of the control equipmentin response to initial slipping thereof. The sanding means is further operative to continue supplying sand to the rails during operation-of the brake control equipment to eect the release of the brakes, or until the associated Wheel has resumed the speed corresponding to the speed of the vehicle.

While `one illustrative embodiment of the invention has been described in detail, it is not intended to limit the invention to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. Vehicle brake and sanding control apparatus comprising, in combination, manually operated means for controlling the application and release of the brakes associated with a wheel of the vehicle, means operative to effect sanding, brake control means operative while the manually operative means is conditioned to cause application of the brakes to effect release of the brakes and subsequent reapplication thereof, and means responsive to the rotative deceleration of the vehicle wheel at a rate in excess of a certain rate for effecting operation of said sanding means and responsive to rotative deceleration of the vehicle wheel at a second certain rate higher than the first certain rate for effecting operation of the brake control means.

2. Vehicle brake and sanding control apparatus comprising, in combination, manually operative means for controlling the application and release of the brakes associated with a wheel 0 of the vehicle, means for eifecting sanding, brake control means operative, while the manually operative means is conditioned to cause application of the brakes, to effect a release of the brakes and subsequent reapplication thereof, and means controlled in accordance with the rate of rotative deceleration of the Wheel for effecting sequential operation of said sanding means and brake control means.

3. Vehicle brake and sanding control apparatus comprising, in combination, manually operative means for controlling application and release of the wheel brakes of the vehicle, means operative to effect sanding, brake control means operative, while the manually operative means is conditioned to cause application of the brakes, to effect the release of the brakes and the subsequent reapplication thereof, means responsive to the rate of deceleration of a vehicle wheel, and means controlled by the last said means for effecting operation of the sanding means and the brake control means in succession in the order named.

l. Vehicle brake and sanding control apparatus comprising, in combination, manually operative means for controlling the application and release of the brakes associated with a wheel of the vehicle, means operative to eiect sanding, braking control means operative, while the manually operative means is conditioned to cause application of the brakes, to eifect release of the brakes and subsequent reapplication thereof, means controlled according to the rate of rotative deceleration of the wheel for effecting operation of said sanding means and said brake contro-l means in succession, and means effective, once the brake control means is operated to effect release of the brakes, to prevent subsequent operation thereof to effect reapplication of the brakes until the rotative speed of the wheel corresponds to the speed of the Vehicle.

5. A brake and sanding control equipment adapted for association with the brakes for a vehicle wheel, comprising brake release means operative to effect the release of the brakes, a pair of sanding devices operative to supply sand at opposite sides of said wheel, directional control means normally conditioned to render one of said sanding devices operable and the other inoperable and responsive to an increase in fluid catasto pressure to reverse the operating condition of said sanding devices, fluid pumping means driven by said wheel and operative according to rotation thereof in one direction to supply fluid under pressure to a chamber and according to rotation of said wheel in the opposite direction to supply uid under pressure to said chamber and to said directional control means, whereby the sanding mechanism in advance of the wheel is always conditioned for operation, and means responsive to a sudden reduction in the pressure of fluid in said chamber to effect operation of the operative sanding mechanism and of said brake release means.

6. In a sanding control equipment for association with a vehicle wheel: sanding means, and sanding control means cooperative therewith to govern the supply of sand in advance of the wheel, said sanding control means including a pump driven by said wheel for supplying liquid under a pressure varying in accordance with the speed thereof, a spring, movable abutment means subject to the opposing pressures of said spring and of the liquid supplied by said pump for controlling a discharge communication therefor, a piston movable relatively to the abutment means and operative to actuate said brake control means, means for entrapping liquid between said abutment means and said piston to render the piston responsive to quick movement of the abutment means, and means for gradually releasing said liquid during slow movement of the abutment means. f

7. Sanding control apparatus for governing the deposition of sand in advance of a vehicle wheel, comprising sand supply means, speed responsive mechanism operative to establish a fluid pressure proportional to the rotative speed of said wheel, a movable abutment subject to said fluid pressure and to a substantially constant opposing pressure, any element movable by said abutment through a chamber adapted to contain a quantity of liquid, means for effecting restricted flow of liquid from one side of said element to the other during normal gradual movement thereof by said abutment, and means for actuating said sand supply means including a piston subject to the pressure of liquid entrapped at one side of said element, upon sudden movement thereof due to a change in the rotative speed of said wheel at an undesirable rate.

8. Sanding control apparatus for governing the supply of sand in advance of a wheel of a railway truckhaving a journal box, comprising sand supply means, a casing structure adapted to-be carried by the journal box associated with the wheel and having formed therein a liquid supply reservoir and a pressure chamber, a pump mounted in said casing structure and operative to supply liquid from said reservoir to said chamber at a rate proportional to the rotative speed of said wheel, a movable abutment controlling a return passage from said chamber to said reservoir and movable through a range of positions corresponding to variations in the pressure of liquid in said chamber, and means responsive to hydraulic pressure created upon sudden movement of said abutment from one position to another for actuating said sand supply means.

BURTON S, AIKMAN. 

